This invention relates generally to discharge devices, and more particularly to discharge devices having an emissive cathode.
Fast switching devices in integrated circuits are customarily made with semiconductor materials as the active device medium with pn junctions and metal-oxide-semiconductor or metal-semiconductor (Schottky barrier) junctions which regulate the flow of electrons and/or holes between emitter and collector or between source and drain regions within the semiconductor.
Velocity saturation, heat dissipation, radiation effects, fluctuation phenomena, and device dimensions (e.g., gate length) provide the known basic limitations to this technology.
In contrast to such devices, in which the semiconductor constitutes the active device medium, there have also been demonstrated vacuum integrated circuits in which the active device medium is the vacuum and in which the emitter contacts are the usual thermionic cathode emitters. These vacuum integrated circuits have the following limitations: slow speed because of space charge screening; large macroscopic dimensions resulting from current requirements and ad hoc fabrication methods; running the entire device at high temperatures in order to keep the cathode emitting; and high cost and nonreproducible fabrication because silicon fabrication technology is not used.